InputDevice: return std::optional from getAbsoluteAxisInfo

This also allows us to remove the valid field from RawAbsoluteAxisInfo,
since we can represent "invalid" axes (which usually just meant absent
ones) using std::nullopt.

Test: atest inputflinger_tests
Test: m checkinput
Test: Check "Raw Touch Axes" section of touch input mapper info in
      dumpsys input
Bug: 245989146
Flag: EXEMPT refactor
Change-Id: I045a2e0b61a84657f2f8171c1fee3cc3e331ac86
diff --git a/services/inputflinger/reader/mapper/ExternalStylusInputMapper.cpp b/services/inputflinger/reader/mapper/ExternalStylusInputMapper.cpp
index 3af1d04..7cc8940 100644
--- a/services/inputflinger/reader/mapper/ExternalStylusInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/ExternalStylusInputMapper.cpp
@@ -33,7 +33,7 @@
 
 void ExternalStylusInputMapper::populateDeviceInfo(InputDeviceInfo& info) {
     InputMapper::populateDeviceInfo(info);
-    if (mRawPressureAxis.valid) {
+    if (mRawPressureAxis) {
         info.addMotionRange(AMOTION_EVENT_AXIS_PRESSURE, AINPUT_SOURCE_STYLUS, 0.0f, 1.0f, 0.0f,
                             0.0f, 0.0f);
     }
@@ -50,7 +50,7 @@
 std::list<NotifyArgs> ExternalStylusInputMapper::reconfigure(nsecs_t when,
                                                              const InputReaderConfiguration& config,
                                                              ConfigurationChanges changes) {
-    getAbsoluteAxisInfo(ABS_PRESSURE, &mRawPressureAxis);
+    mRawPressureAxis = getAbsoluteAxisInfo(ABS_PRESSURE);
     mTouchButtonAccumulator.configure();
     return {};
 }
@@ -82,10 +82,10 @@
         mStylusState.toolType = ToolType::STYLUS;
     }
 
-    if (mRawPressureAxis.valid) {
+    if (mRawPressureAxis) {
         auto rawPressure = static_cast<float>(mSingleTouchMotionAccumulator.getAbsolutePressure());
-        mStylusState.pressure = (rawPressure - mRawPressureAxis.minValue) /
-                static_cast<float>(mRawPressureAxis.maxValue - mRawPressureAxis.minValue);
+        mStylusState.pressure = (rawPressure - mRawPressureAxis->minValue) /
+                static_cast<float>(mRawPressureAxis->maxValue - mRawPressureAxis->minValue);
     } else if (mTouchButtonAccumulator.hasButtonTouch()) {
         mStylusState.pressure = mTouchButtonAccumulator.isHovering() ? 0.0f : 1.0f;
     }